Well, for example the government could have a series of incentives to build or retrofit houses to have much less energy use. There was a solar power credit in the US for a number of years, but the technology wasn't developed enough at the time for the program to do much.

There could be efforts to have local wind generators for small communities, rather than only focusing on wind farms. (I don't consider personal windmills practical in most cases.) Communities were happy enough to erect mobile phone towers all over the landscape even when opposed by people who disliked the aesthetic impact, so when there is a will there is a way.

Car pooling could be encouraged via meaningful subsidies. For example a person could get a multi-seat van (say 7-9 passengers) for little or no money and then act as a small scale quasi-public commuting service.

On the demand side certain behaviors could be discouraged. For example the bottled water fad is totally senseless. This should be stopped. Aside from those who want water as an individual drink in preference to some carbonated alternative there is no reason for people with municipal water systems to be buying water for the home. Actually the entire soft drink industry is a bad idea. People survived on plain water from a tap for a long time before Coca Cola. How about encouraging this with a program to install public water fountains?

I've always envisioned a commuter vehicle smaller than the Smart Car that would be driven to the local rail station and then onto a special flatbed car. One would stay in one's vehicle while the train went into the downtown and then drive off to go the last mile.

Bringing back pushcart vendors (except this time with trucks) that drive into an exurban neighborhood several times a week with perishables like milk, butter, eggs and bread would cut down on trips to the supermarket. The same could be done for vegetables. The popularity of farmer's markets shows that there is a demand.

The cost of disposal of recyclable items should be built into the original price. This might be refunded when the item is brought in for recycling or just used to finance the operation. I know that the EU is working on some ideas in this direction, but mostly for electronics and autos.

Packaging could be redesigned. Only one chain in the US (Costco) doesn't provide shopping bags for groceries. People can bring their own or use the empty boxes that the store received merchandise in.

Much packaging is meant for shelf appeal and gets discarded immediately upon opening the item. Why not one display item and then the take home copies are in a simpler package like a plastic or paper bag (or nothing in the case of things which are already packaged like toothpaste).

If we held a contest to come up with ideas like these I'm sure we would get many suggestions. People know what makes sense they just haven't been asked for their input.